A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . case is now composed entirely of investment-compound, and ready forpouring the first metal cast A. Before drying the investment-models for this pur-pose, it is always advisable at this stage to make new exact duplicates of the originalplaster model A, in case the original is broken. This is easily done by pouring newplaster halves of the model A in the spaces which they occupied, commencingas arranged for the metal cast in Figs. 35 and 36. CHAPTER VI TECHNICS OF THE METAL CASTS
A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . case is now composed entirely of investment-compound, and ready forpouring the first metal cast A. Before drying the investment-models for this pur-pose, it is always advisable at this stage to make new exact duplicates of the originalplaster model A, in case the original is broken. This is easily done by pouring newplaster halves of the model A in the spaces which they occupied, commencingas arranged for the metal cast in Figs. 35 and 36. CHAPTER VI TECHNICS OF THE METAL CASTS AND OBTURATOR The metal casts of the right and left plaster models A are obtained as follows:With the investments in place in the flask, as shown in Fig. 36, and the nasal coversecured in position with the pins, thoroughly dry the case until not a particle ofmoisture appears on a cool dry piece of glass. Haskells Babbitt metal has beenfound to produce the most satisfactory castings. This is especially mentioned,as there is such a vast difference in the general commercial product of this metal. Fig. 35. Fig. It possesses a favorable degree of fusibility and should make a sharp casting with-out shrinkage. During the pouring, hold the case in one hand with a padded hold-er, with the thumb pressing firmly the palatal investment E, and jog the case bystriking the back of the hand upon the bench. This will cause the metal to flowsharply and the air bubbles to rise to the top in case of air pockets. Before themetal has congealed, the excess should be quickly scraped off even with the top ofthe flask. One should never get discouraged if he has to pour several casts beforeone is secured that is perfect, though this may rarely happen. 466 CHAPTER VI. TECHNICS OF THE METAL CASTS AND OBTURATOR 467 After pouring, as soon as the casting has cooled sufficiently, remove the invest-ments and metal cast A, from the lingual half of the flask by gently tapping theflask on the side so that the
Size: 1761px × 1419px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidpracticaltre, bookyear1921
